[R] CairoPDF and greek letter spacing

[David Winsemius]

On Jan 9, 2012, at 8:19 PM, Rolf Turner wrote:

> On 10/01/12 11:40, John Walker wrote:
>> I have a small problem with R graphics output. When I use the lattice
>> package and CairoPDF to generate publication quality graphs I often  
>> use
>> the expression to create an axis title that has microlitres or
>> micrometers as a unit. I use something like the following
>> 'expression(paste("Length (", mu,"m )"))' as an argument to the  
>> xlabel
>> function. The command works but the mu and 'm' have a space between
>> them. It looks like 'u m' rather than 'um'. It only seems to happen  
>> with
>> the CairoPDF output on my linux machine, it's fine on the X11 device.
>> I've fixed it in the past by importing the pdf into inkscape and
>> manually adjusting the spacing (it's more difficult than it sounds
>> because I can't actually adjust the spacing but have to delete the mu
>> and re-enter it).  Is there something I'm doing wrong? Is this a  
>> known
>> bug?  How can I fix it?
> I can't help, but I can confirm the problem, for what *that* is worth.
>
> It seems be an unfortunate interaction between lattice graphics and
> the cairo_pdf() device.
>
> The space between the "mu" and the "m" does not appear with
> ``ordinary'' R graphics, irrespective of device, nor does it appear
> with lattice graphics and, e.g. the pdf() device.  But it does appear
> with lattice graphics *and* the cairo_pdf() device.
>
> That probably means that the problem is subtle and will be difficult
> to impossible to fix. :-(

Doubtful. Do either of you realize that `paste` is a plotmath function  
that is misused more often than correctly used (at least as judged by  
the number o errors submitted to r-help)? I see no workable example,  
but if I did I would be trying instead :

expression(Length~mu*m)

-- 
David Winsemius, MD
West Hartford, CT